Christopher Columbus is considered a hero because he traveled to the New World and launched a series of expeditions and migrations. The money he brought to European empires gave him the status of a hero. However, modern histories are more critical than previous historians.
Christopher Columbus was not the first European to set foot on the New World, as Viking travelers had landed in what is now Canada 500 years before his arrival. However, voyages to the New World began after his arrival. Because of this, he is heralded with launching a new phase of human civilization.
For those who benefited from the resources and land acquired during the colonization and settlement of the new world, he was regarded as a hero. To native populations, however, he was often viewed as a villain. Columbus exploited native people for their resources and labor, and many died because of diseases Europeans introduced and from outright cruelty. His arrival heralded a new age of violence and subjugation.
Western histories often had a positive view of Columbus, and countries and cities have been named after him. The United States even recognizes a Christopher Columbus national holiday. Modern historians, however, now take a more nuanced view, and many condemn him for his cruel actions.